Combustion-driven flow reactor studies of thermal DeNO x reaction kinetics

Abstract

A combustion-driven flow reactor (CDFR) has been developed and employed in an investigation of Thermal DeNo x reaction kinetics. The CDFR consists of a laminar flat-flame burner, an ammonia injection section, and a plug-flow reactor section. Concentrations of NO, NH 3, OH, and reactor temperature were measured along the CDFR centerline, providing a Thermal DeNO x data base over the temperature range 1050K to 1450K, for β between 1 and 3 ( β ≡ injected [NH 3] initial [NO] ). The data were modeled using a 55 reaction chemical kinetics mechanism, taken primarily from the work of Miller and coworkers. Key reactions in the model were found to be NH 2 + OH = NH 2 + H 2O , NH 2 + OH = NH + H 2O , N 2H + M = N 2 + H + M . Optimal fits to data were achieved with a radical branching ratio α, defined by α ≡ k 21 (k 22 + k 21) , with α = 0.48 at 1050K, rising to α ≥ 0.8 at 1400K, and with k 10 = 6.0 × 10 12 mole/cm 3 s.